This invention relates to the sensing of the density of rod-like material and to the controlling of the density thereof, and especially in the field of textile fibers this invention particularly relates to sensing the density of slivers produced by textile machines and to the controlling of the sliver density by controlling the input speed of the machine.
While the invention is particularly described below relative to a carding machine or card, it will be appreciated that the invention extends to other types of textile processing equipment, such as drawframes and pin drafters, which also produce slivers.
As above indicated, besides relating to the sensing to sliver density, this invention also relates to the controlling of that density, i.e., to the automatic leveling of the density of the sliver produced by a textile machine or to rod-like material produced by other machines such as cigarette making machines. Automatic sliver leveling equipment for cards and other textile machines and machines in other fields are in general well known and are frequently referred to as "autolevelers". For example, the Zellweger Ltd. company of Uster, Switzerland advertises a card sliver leveling device under the name "Uster's Control Card System", with an indication that sliver weight never exceeds .+-. 2%. Used in such systems to measure the cross section of the sliver is a pneumatic sensing trumpet or funnel-shaped nozzle such as shown in the Uster British Pat. No. 1,137,297 and also in U.S. Pat. No. 3,435,673 granted Apr. 1, 1969. Those patents review many of the prior art ways of sensing variation in the substance cross-section of textile material, slivers in particular, and of course describe in detail the Uster pneumatic way of measuring sliver cross-sections. Cross-sectional measurement by such prior art does in fact appear to measure sliver density effectively, or sliver weight if the thickness is held uniform. For reasons stated in those patents, the various measuring systems prior to the pneumatic measuring system have disadvantages and obviously so does the latter, which it is an object of the present invention to obviate. In particular, the present invention measures the density of a sliver or other rod-like material by employing compression waves in the sonic or ultrasonic range of frequencies, in order to secure an improved sensing of the density variations which may occur therein.
Use of sonic and ultrasonic beams or waves to sense the density of a fiber mass has heretofore been used by the assignee hereof, for example, as shown in the Lytton et al U.S. Pat. No. 3,158,291, in a card feeder for purposes of controlling the density and thickness of the web produced by that feeder. In addition, others have employed variable speed drives between the doffer and feed rolls in cards, and have controlled therewith the input speed of the feed roll in response to the sensing of the sliver cross-section, thickness or density by the various ways discussed above. However, to applicant's knowledge, no one heretofore has employed sonic or ultrasonic waves in the manner herein described below in detail to sense the density of slivers or to control the density thereof. Hence, such is the object of this invention in the detail to which the claims define the scope of the invention, which is first described in detail below in reference to the drawings, wherein: